Fuel system detergent and preparation method thereof

Abstract

The invention relates to the technical field of fuel additives, in particular to a fuel system detergent and a preparation method thereof. According to the detergent, molecular structure functional design is adopted, division of labor of low-temperature efficient valve cleaning and high-temperature precipitation control is achieved through synergistic matching of different types of polyether amines, catechol grafted polyether amine with a metal surface conditioning effect is introduced in a matched mode, and the metal surface covering capacity, the oxidation resistance capacity and the long-acting deposition resistance capacity of the detergent are effectively improved. The detergent is superior to a traditional formula in the aspects of reducing deposition of an air inlet valve and a combustion chamber, inhibiting increase of octane number demand, reducing corrosion risk and viscosity increase and the like, and has remarkable improvement and popularization values on engine operation safety and cleanliness.

Description

Technical Field

[0001] This invention relates to the field of fuel additive technology, and in particular to a fuel system detergent and its preparation method. Background Technology

[0002] With the rapid development of the automotive industry and increasingly stringent emission standards, fuel system detergents are playing an increasingly important role in maintaining engine performance and reducing harmful emissions. Traditional fuel detergents mainly target the cleaning of intake valve deposits (IVD), but in practical applications, a long-standing technical contradiction has been discovered in the industry: while effectively cleaning intake valve deposits, detergents often lead to an increase in combustion chamber deposits (CCD), which in turn causes an increase in engine octane requirement (ORI) and a decrease in knock margin.

[0003] The root cause of this technical contradiction lies in the limitations of the molecular structure of traditional detergents. Currently, the commonly used single polyetheramine (PEA) detergent systems or detergent systems based on polyisobutyleneamine (PIBA) have significant shortcomings in molecular design: their molecular structures lack differentiated functional designs for different temperature regions, failing to simultaneously meet the dual requirements of low-temperature intake valve cleaning and high-temperature combustion chamber deposit inhibition. Specifically, while traditional detergents can effectively dissolve and clean deposits when the intake valve area is relatively low, these cleaned deposit precursors, lacking effective high-temperature dispersion and resuspension capabilities, are prone to redepositing in the combustion chamber and forming a more stable carbon deposit structure.

[0004] Traditional polyetheramine molecules have a simple structure and a wide molecular weight distribution, lacking targeted functional group modification, resulting in insufficient thermal stability and dispersion performance in high-temperature combustion environments. Especially under the high-temperature and high-pressure conditions inside the combustion chamber, traditional detergent molecules are prone to thermal decomposition and oxidation reactions. The resulting decomposition products become new deposit precursors, not only failing to inhibit the formation of combustion chamber deposits but also exacerbating carbon buildup. This "detergent-cleaning-carbon-increasing" phenomenon severely affects the overall effectiveness of the detergent, leading to problems such as decreased power, increased fuel consumption, and increased knocking tendency in engines after long-term use of detergents.

[0005] Another key technical challenge lies in the lack of effective conditioning capabilities of traditional cleaning agents for metal surfaces. Metal surfaces inside engines (such as intake valves, combustion chamber walls, and fuel injectors) are prone to oxide film formation and increased micro-roughness under high temperature, high pressure, and corrosive environments, providing favorable conditions for deposit adhesion. While traditional cleaning agents possess some cleaning ability, they lack long-term protection and conditioning functions for metal surfaces, causing deposits to quickly re-accumulate on the cleaned surface, making the cleaning effect unsustainable.

[0006] In terms of solvent carrier systems, traditional detergent products typically use simple solvent systems and lack systematic compatibility design. In the complex component environment of commercial gasoline, they are prone to technical defects such as compatibility problems, increased water sensitivity, and aggravated corrosion, which affect the overall performance and application reliability of the products.

[0007] Therefore, how to design a new type of fuel system detergent that can effectively clean intake valve deposits and simultaneously inhibit the increase of combustion chamber deposits has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a fuel system detergent and its preparation method, so as to avoid the technical contradiction that the fuel detergent causes an increase in combustion chamber deposits and thus an increase in octane demand when cleaning intake valve deposits.

[0009] To achieve the above objectives, the present invention provides a fuel system detergent prepared from the following raw materials in parts by weight: 100-150 parts of terminal amino polyether A, 150-200 parts of terminal amino polyether B, 2-5 parts of catechol-grafted polyether amine, 440-460 parts of toluene, 190-210 parts of heavy aromatic oil, 12-18 parts of 2,6-di-tert-butyl-4-methylphenol, 7-9 parts of N,N'-disalicylic acid-1,2-propanediamine, and 20-30 parts of isopropanol.

[0010] The terminal amino polyether A is obtained by ring-opening polymerization of propylene oxide with methanol as an initiator in the presence of a bimetallic cyanide catalyst to obtain terminal hydroxyl polypropylene glycol, and then amination of the terminal hydroxyl polypropylene glycol with anhydrous ammonia by passing hydrogen gas through it in the presence of Raney nickel.

[0011] The terminal amino polyether B is obtained by: taking terminal amino polyether A and styrene carbonate to introduce a phenyl side chain through amino ring opening to form a terminal hydroxy carbamate, and then continuing to grow the chain with propylene oxide in the presence of a bimetallic cyanide catalyst to obtain a chain extension product. The chain extension product is then subjected to secondary amination with hydrogen gas and anhydrous ammonia in the presence of Raney nickel to obtain terminal amino polyether B.

[0012] The catechol-grafted polyetheramine is a grafted product obtained by reacting terminal amino polyether B with dopamine glycidyl ether in dimethylformamide in the presence of triethylamine, followed by solvent removal, precipitation washing, and drying.

[0013] Preferably, the raw materials for preparing the terminal hydroxyl polypropylene glycol are, by weight, 20 parts methanol, 4 parts bimetallic cyanide catalyst and 200-280 parts propylene oxide.

[0014] Preferably, the raw materials for preparing the terminal amino polyether A are, by weight, 300 parts of terminal hydroxyl polypropylene glycol and 14-18 parts of Raney nickel.

[0015] Preferably, the hydrogen partial pressure during the preparation of the terminal amino polyether A is 2.8-3.2 MPa, and the total pressure is 5.8-6.5 MPa.

[0016] Preferably, the raw materials for preparing the chain extension product are, by weight, 180 parts of terminal amino polyether A, 50-80 parts of styrene carbonate, 1.5-2.5 parts of bimetallic cyanide catalyst, and 40-80 parts of propylene oxide.

[0017] Preferably, the raw materials for preparing the terminal amino polyether B are, by weight, 200-240 parts of chain extension product and 10-14 parts of Raney nickel.

[0018] Preferably, the hydrogen partial pressure during the preparation process of the terminal amino polyether B is 2.8-3.2 MPa, and the total pressure is 5.8-6.5 MPa.

[0019] Preferably, the raw materials for preparing the catechol-grafted polyetheramine are, by weight, 20 parts of terminal amino polyether B, 2-5 parts of dopamine glycidyl ether, 120 parts of dimethylformamide and 1.5-2.5 parts of triethylamine.

[0020] Furthermore, the present invention also provides a method for preparing a fuel system detergent, comprising the following steps: (1) Preparation of bimetallic cyanide catalyst: Zinc chloride was dissolved in deionized water, and potassium hexacyanocobaltate was dissolved in deionized water and then slowly added to the above solution. Tert-butanol and polyethylene glycol 400 were added and stirred for 100-140 min. The mixture was then allowed to stand for aging, filtered and washed alternately with deionized water and tert-butanol, and dried under reduced pressure to obtain the bimetallic cyanide catalyst. (2) Preparation of terminal hydroxyl polypropylene glycol: Methanol is added as an initiator and a bimetallic cyanide catalyst in a pressure-resistant reactor, propylene oxide is introduced, and the reaction is carried out under heating and stirring conditions. The reaction temperature is 85-95℃ and the time is 150-210min. Unreacted methanol and trace monomers are removed under reduced pressure, and the catalyst is removed by filtration to obtain terminal hydroxyl polypropylene glycol. (3) Preparation of terminal amino polyether A: Terminal hydroxyl polypropylene glycol and Raney nickel are loaded into a pressure-resistant reactor, hydrogen and anhydrous ammonia are introduced to pressurize the reactor, and the reaction is carried out under heating and stirring conditions. The reaction temperature is 125-135℃ and the time is 210-270min. The reactor is cooled, vented and filtered, and residual ammonia and water are removed under reduced pressure to obtain terminal amino polyether A. (4) Introducing phenyl side chain and chain growth: Add styrene carbonate to the terminal amino polyether A, stir and react at 75-85℃ for 150-210 min to generate terminal hydroxyl carbamate with phenyl side chain from the terminal amino ring-opening cyclic carbonate. Then add bimetallic cyanide catalyst and propylene oxide and chain grow at 85-95℃ for 150-210 min to obtain chain-extended product; (5) Preparation of terminal amino polyether B: The chain extension product and Raney nickel are loaded into a pressure-resistant reactor, hydrogen and anhydrous ammonia are introduced to pressurize the reactor, and the reaction is carried out at 125-135℃ for 210-270 min to complete the amination. The reactor is cooled, filtered and the residual ammonia is removed under reduced pressure to obtain terminal amino polyether B. (6) Preparation of dopamine glycidyl ether: Dopamine hydrochloride and sodium hydroxide were dissolved in deionized water, and epichlorohydrin was added dropwise after cooling. The mixture was stirred at 30°C for 360 min, extracted with ethyl acetate, washed with water, and the solvent was removed by vacuum evaporation to obtain dopamine glycidyl ether. (7) Preparation of catechol-grafted polyetheramine: terminal amino polyether B and dopamine glycidyl ether are dissolved in dimethylformamide, triethylamine is added, and the reaction is stirred at 45-55℃ for 210-270 min to complete the grafting. After removing the solvent under reduced pressure, the product is precipitated with anhydrous diethyl ether, washed and dried to obtain catechol-grafted polyetheramine. (8) Preparation of detergent: Terminal amino polyether A, terminal amino polyether B and catechol-grafted polyether amine are stirred evenly at 40°C to obtain a mother liquor. Toluene, heavy aromatic oil, 2,6-di-tert-butyl-4-methylphenol, N,N'-disalicylic acid-1,2-propanediamine and isopropanol are added and stirred at room temperature. The mixture is allowed to stand to degas and then filtered to obtain a fuel system detergent.

[0021] Preferably, in step (6), by weight, there are 15 parts of dopamine hydrochloride, 6 parts of sodium hydroxide, 80 parts of deionized water, and 25 parts of epichlorohydrin.

[0022] This invention, through innovative molecular structure design and preparation process, successfully resolves the technical contradiction of traditional fuel detergents increasing carbon buildup in intake valves, achieving synergistic optimization of intake valve cleaning and combustion chamber deposit control, resulting in significant beneficial effects: The functional design of the molecular structure yielded the following results: Polyetheramine B was constructed by introducing a phenyl side chain through ring-opening of a cyclic carbonate. This phenyl side chain exhibits excellent affinity and solubility for polycyclic aromatic hydrocarbon deposition precursors in a high-temperature combustion environment. It can maintain the generated fine carbon nuclei in a dispersed state and carry them away from the combustion zone with the airflow, fundamentally inhibiting the formation of combustion chamber deposits. Simultaneously, the ratio of A / B polyetheramines was optimized to achieve functional differentiation in different temperature zones: polyetheramine A efficiently cleans valve back deposits at lower temperatures, while polyetheramine B maintains strong dispersion properties at higher temperatures, forming a continuous coverage of low-temperature valve cleaning and high-temperature sediment control.

[0023] Metal surface conditioning and long-term protection: The introduced catechol-grafted polyetheramine forms stable multi-point coordination adsorption with the metal / oxide surface through the ortho- and tho-diol groups, significantly improving the instantaneous coverage and wetting properties of the surface, effectively weakening the adhesion strength of the deposition precursor, and maintaining the trace deposits in an easily peelable state. This coordination adsorption structure also has excellent antioxidant properties, capable of capturing free radicals and inhibiting the peroxidation and cross-linking reactions of fuel under thermal stress, thereby reducing the formation of adhesive deposits.

[0024] Improved controllability of molecular structure and thermal stability: Narrowly distributed polyetheramines prepared using bimetallic cyanide catalysts exhibit a more uniform molecular structure and controllable molecular kinematic behavior during combustion and volatilization, effectively reducing the formation of secondary deposition precursors. The narrow molecular structure also improves the dispersion stability and interfacial activity of the detergent in fuel, enhancing cleaning efficiency and durability.

[0025] Synergistic optimization of multiple indicators: This invention achieves synergistic optimization of multiple technical objectives, including intake valve deposit cleaning, combustion chamber deposit inhibition, octane demand control, and improved thermal stability. Through precise molecular structure design, the detergent can achieve optimal performance under different operating conditions and temperatures, avoiding the technical defect of traditional products where optimizing a single indicator leads to the deterioration of other indicators.

[0026] Enhanced system compatibility and stability: Through the synergistic design of toluene as the main solvent, heavy aromatic oil carrier, BHT antioxidant, corrosion inhibitor, and anti-icing agent, the compatibility and dispersion stability of the detergent in commercial gasoline are significantly improved, water sensitivity and corrosion risk are reduced, and the reliability and safety of the product in practical applications are ensured. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0028] Figure 1 This is the ultraviolet absorption spectrum of terminal amino polyether B and catechol-grafted polyetheramine in Example 2 of the present invention; Figure 2 This is a gel permeation chromatogram of terminal amino polyether A and terminal amino polyether B in Example 2 of the present invention; Figure 3 The infrared absorption spectra of terminal amino polyether A and terminal amino polyether B in Example 2 of the present invention are shown. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] Example 1: (1) Add 14g of zinc chloride to 100g of deionized water and stir evenly. Dissolve 8g of potassium hexacyanocobaltate in 80g of deionized water to prepare a solution and slowly pour it into the above solution. Add 40g of tert-butanol and 5g of polyethylene glycol 400 and continue stirring for 100min. Let it stand for aging. After filtration, wash it three times with deionized water and tert-butanol alternately. Dry it under reduced pressure at 50°C to obtain the bimetallic cyanide catalyst. (2) Add 20g of methanol as an initiator and 4g of bimetallic cyanide catalyst to a pressure-resistant reactor, and introduce 200g of propylene oxide. Stir the reaction at 85°C for 150min, remove unreacted methanol and trace monomers under reduced pressure, filter to remove catalyst, and obtain terminal hydroxyl polypropylene glycol. (3) 300g of terminal hydroxyl polypropylene glycol and 14g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 2.8MPa, and then anhydrous ammonia was introduced to a total pressure of 5.8MPa. The reaction was stirred at 125°C for 210min. After the reaction, the temperature was slowly lowered to 40°C, and the pressure was vented to 0.1MPa. The catalyst was removed by filtration and the residual ammonia and moisture were removed by depressurization to obtain terminal amino polyether A. (4) Add 50g of styrene carbonate to 180g of terminal amino polyether A, stir at 75°C for 150min to generate terminal hydroxyl carbamate with phenyl side chain from the terminal amino ring-opening cyclic carbonate, then add 1.5g of bimetallic cyanide catalyst and 40g of propylene oxide, continue ring-opening growth at 85°C for 150min to obtain chain-extended product; (5) 200g of chain extension product and 10g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 2.8MPa, and then anhydrous ammonia was introduced to a total pressure of 5.8MPa. The reaction was stirred at 125°C for 210min to complete amination. The mixture was cooled, filtered, and the residual ammonia was removed under reduced pressure to obtain terminal amino polyether B. (6) In a three-necked flask, 15g of dopamine hydrochloride and 6g of sodium hydroxide were dissolved in 80g of deionized water. After stirring evenly, the temperature was lowered to 5°C. 25g of epichlorohydrin was added dropwise and the mixture was stirred at 30°C for 360min. Ethyl acetate was added for extraction and the mixture was washed three times with deionized water. The solvent was removed by vacuum evaporation to obtain dopamine glycidyl ether. (7) Dissolve 20g of terminal amino polyether B and 2g of dopamine glycidyl ether in 120g of dimethylformamide, add 1.5g of triethylamine as a catalyst, stir at 45°C for 210min to complete the grafting, remove the solvent under reduced pressure, wash with anhydrous diethyl ether precipitate and dry to obtain catechol grafted polyetheramine. (8) 150g of terminal amino polyether A, 150g of terminal amino polyether B and 2g of catechol-grafted polyether amine were thoroughly stirred at 40°C to obtain a fuel system detergent stock solution. Then, 460g of toluene as the main solvent, 190g of heavy aromatic oil as the carrier oil, 12g of 2,6-di-tert-butyl-4-methylphenol as an antioxidant, 7g of N,N'-disalicylic acid-1,2-propanediamine as a corrosion inhibitor and 20g of isopropanol as an anti-icing agent were added. The mixture was thoroughly stirred and mixed at room temperature, allowed to stand to remove bubbles and then filtered to obtain the fuel system detergent.

[0031] Example 2: (1) Add 14g of zinc chloride to 100g of deionized water and stir evenly. Dissolve 8g of potassium hexacyanocobaltate in 80g of deionized water to prepare a solution and slowly pour it into the above solution. Add 40g of tert-butanol and 5g of polyethylene glycol 400 and continue stirring for 120min. Let it stand for aging. After filtration, wash it three times with deionized water and tert-butanol alternately. Dry it under reduced pressure at 50°C to obtain the bimetallic cyanide catalyst. (2) Add 20g of methanol as an initiator and 4g of bimetallic cyanide catalyst to a pressure-resistant reactor, and introduce 240g of propylene oxide. Stir the reaction at 90°C for 180min, remove unreacted methanol and trace monomers under reduced pressure, filter to remove catalyst, and obtain terminal hydroxyl polypropylene glycol. (3) 300g of terminal hydroxyl polypropylene glycol and 16g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 3MPa, and then anhydrous ammonia was introduced to 6MPa. The reaction was stirred at 130°C for 240min. After the reaction, the temperature was slowly lowered to 40°C and vented to 0.1MPa. The catalyst was removed by filtration and the residual ammonia and moisture were removed by depressurization to obtain terminal amino polyether A. (4) Add 65g of styrene carbonate to 180g of terminal amino polyether A, stir at 80°C for 180min to generate terminal hydroxyl carbamate with phenyl side chain from the terminal amino ring-opening cyclic carbonate, then add 2g of bimetallic cyanide catalyst and 60g of propylene oxide, continue ring-opening growth at 90°C for 180min to obtain chain-extended product; (5) 220g of chain extension product and 12g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 3MPa, and then anhydrous ammonia was introduced to a total pressure of 6MPa. The reaction was stirred at 130°C for 240min to complete amination. After cooling and filtration, the residual ammonia was removed under reduced pressure to obtain terminal amino polyether B. (6) In a three-necked flask, 15g of dopamine hydrochloride and 6g of sodium hydroxide were dissolved in 80g of deionized water. After stirring evenly, the temperature was lowered to 5°C. 25g of epichlorohydrin was added dropwise and the mixture was stirred at 30°C for 360min. Ethyl acetate was added for extraction and the mixture was washed three times with deionized water. The solvent was removed by vacuum evaporation to obtain dopamine glycidyl ether. (7) Dissolve 20g of terminal amino polyether B and 3g of dopamine glycidyl ether in 120g of dimethylformamide, add 2g of triethylamine as a catalyst, stir at 50°C for 240min to complete the grafting, remove the solvent under reduced pressure, wash with anhydrous diethyl ether precipitate and dry to obtain catechol grafted polyetheramine. (8) 120g of terminal amino polyether A, 180g of terminal amino polyether B and 3g of catechol-grafted polyether amine were thoroughly stirred at 40°C to obtain a fuel system detergent stock solution. Then, 450g of toluene as the main solvent, 200g of heavy aromatic oil as the carrier oil, 15g of 2,6-di-tert-butyl-4-methylphenol as an antioxidant, 8g of N,N'-disalicylic acid-1,2-propanediamine as a corrosion inhibitor and 25g of isopropanol as an anti-icing agent were added. The mixture was thoroughly stirred and mixed at room temperature, allowed to stand to remove bubbles and then filtered to obtain the fuel system detergent.

[0032] Example 3: (1) Add 14g of zinc chloride to 100g of deionized water and stir evenly. Dissolve 8g of potassium hexacyanocobaltate in 80g of deionized water to prepare a solution and slowly pour it into the above solution. Add 40g of tert-butanol and 5g of polyethylene glycol 400 and continue stirring for 140min. Let it stand for aging. After filtration, wash it three times with deionized water and tert-butanol alternately. Dry it under reduced pressure at 50°C to obtain the bimetallic cyanide catalyst. (2) Add 20g of methanol as an initiator and 4g of bimetallic cyanide catalyst to a pressure-resistant reactor, and introduce 280g of propylene oxide. Stir the reaction at 95°C for 210min, remove unreacted methanol and trace monomers under reduced pressure, filter to remove catalyst, and obtain terminal hydroxyl polypropylene glycol. (3) 300g of terminal hydroxyl polypropylene glycol and 18g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 3.2MPa, and then anhydrous ammonia was introduced to a total pressure of 6.5MPa. The reaction was stirred at 135°C for 270min. After the reaction, the temperature was slowly lowered to 40°C and vented to 0.1MPa. The catalyst was removed by filtration and the residual ammonia and moisture were removed by depressurization to obtain terminal amino polyether A. (4) Add 80g of styrene carbonate to 180g of terminal amino polyether A, stir at 85°C for 210min to generate terminal hydroxyl carbamate with phenyl side chain from the terminal amino ring-opening cyclic carbonate, then add 2.5g of bimetallic cyanide catalyst and 80g of propylene oxide, continue to open the ring for 210min at 95°C to obtain the chain-extended product; (5) 240g of chain extension product and 14g of Raney nickel catalyst (purchased from Inner Mongolia Zhenhao Catalyst, model ZHR-3110) were loaded into a pressure-resistant reactor, hydrogen was introduced to 3.2MPa, and then anhydrous ammonia was introduced to a total pressure of 6.5MPa. The reaction was stirred at 135°C for 270min to complete amination. The mixture was cooled, filtered, and the residual ammonia was removed under reduced pressure to obtain terminal amino polyether B. (6) In a three-necked flask, 15g of dopamine hydrochloride and 6g of sodium hydroxide were dissolved in 80g of deionized water. After stirring evenly, the temperature was lowered to 5°C. 25g of epichlorohydrin was added dropwise and the mixture was stirred at 30°C for 360min. Ethyl acetate was added for extraction and the mixture was washed three times with deionized water. The solvent was removed by vacuum evaporation to obtain dopamine glycidyl ether. (7) Dissolve 20g of terminal amino polyether B and 5g of dopamine glycidyl ether in 120g of dimethylformamide, add 2.5g of triethylamine as a catalyst, stir at 55°C for 270min to complete the grafting, remove the solvent under reduced pressure, wash with anhydrous diethyl ether precipitate and dry to obtain catechol grafted polyetheramine. (8) 100g of terminal amino polyether A, 200g of terminal amino polyether B and 5g of catechol-grafted polyether amine were thoroughly stirred at 40°C to obtain a fuel system detergent stock solution. Then, 440g of toluene as the main solvent, 210g of heavy aromatic oil as the carrier oil, 18g of 2,6-di-tert-butyl-4-methylphenol as an antioxidant, 9g of N,N'-disalicylic acid-1,2-propanediamine as a corrosion inhibitor and 30g of isopropanol as an anti-icing agent were added. The mixture was thoroughly stirred and mixed at room temperature, allowed to stand to remove bubbles and then filtered to obtain the fuel system detergent.

[0033] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that in step (8), the catechol-grafted polyetheramine was replaced with an equal mass of terminal amino polyether B, and the other conditions were the same as in Example 2.

[0034] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that in step (4), ethylene carbonate is replaced with styrene carbonate in equal mass to obtain the corresponding product without phenyl side chains, while the other conditions are the same as in Example 2.

[0035] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that in step (8), terminal amino polyether A of equal mass is used instead of terminal amino polyether B, and the other conditions are the same as in Example 2.

[0036] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that in step (8), terminal amino polyether B of equal mass is used instead of terminal amino polyether A, and the other conditions are the same as in Example 2.

[0037] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that in step (4), the chain growth monomer is replaced by 60g of ethylene oxide instead of 60g of propylene oxide, and the other conditions are the same as in Example 2.

[0038] Performance testing: Ultraviolet absorption spectroscopy test: Tested using a CARY5000 ultraviolet spectrophotometer.

[0039] Gel permeation chromatography test: The test was performed using a Waters ACQUITY UPLC gel permeation chromatograph.

[0040] Infrared absorption spectroscopy test: The test was conducted using a Bruker Alpha Fourier transform infrared spectrometer.

[0041] Intake valve deposit test: The test was conducted according to the national standard GB / T 19230.5-2003. A Ford 2.3L four-cylinder engine was used as the test bench. The test conditions were: engine speed 2500±50 r / min, intake manifold absolute pressure 55±2 kPa, engine coolant temperature 88±3℃, and intake air temperature 52±3℃. The fuel system detergents prepared in the examples and comparative examples were added to the base gasoline at a concentration of 200 mg / L, and a 100-hour continuous operation test was conducted at the same concentration as the comparative examples. After the test, the engine was disassembled, cleaned, and the deposits on the surface of each intake valve were weighed. The results are shown in Table 1.

[0042] Combustion chamber deposit test: The test was conducted according to the national standard GB / T 19230.5-2003. After completing the intake valve deposit test, the carbon deposits in the engine combustion chamber were quantitatively analyzed. The total amount of deposits on the top of the combustion chamber, the piston top surface, and the cylinder wall was determined using solvent extraction and gravimetric methods. The test conditions were kept consistent with the intake valve test, and the test duration was 100 hours. The results are shown in Table 1.

[0043] Octane demand growth control effect test: The research octane number (RON) was determined according to ASTM D2699 standard. The effect of detergent on octane demand growth was evaluated by engine bench test. The same Ford 2.3L engine was used and operated for 200 hours under standard test conditions. The change in the engine's fuel octane demand was measured. The results are shown in Table 1.

[0044] Stability testing: A method for evaluating the thermal stability of detergents was established based on the principles of the petrochemical industry standard SH / T 0175. Each sample was heated at 180℃ for 4 hours, and the viscosity changes before and after heating were measured. The results are shown in Table 1.

[0045] Metal corrosion test: The copper sheet corrosion test was carried out according to GB / T 5096-2017. After treatment at 50℃ for 3 hours, the degree of corrosion of the metal sheet was observed and the grade was evaluated. The results are shown in Table 1.

[0046] Table 1 Performance Test Results Sample Intake valve deposit weight / mg / valve Combustion chamber deposit weight (mg / valve) Octane number demand growth / RON Viscosity growth rate / % Corrosion level Example 1 34 392 2.0 7.9 1a Example 2 27 344 1.5 6.8 1a Example 3 30 362 1.7 7.2 1a Comparative Example 1 45 434 2.9 9.6 1a Comparative Example 2 49 482 3.4 12.4 1b Comparative Example 3 41 411 2.4 8.8 1a Comparative Example 4 38 382 2.1 9.1 1a Comparative Example 5 62 546 4.1 19.7 1b Data Analysis: As can be seen from the data in Examples 1-3 in Table 1, the fuel system detergent prepared by this invention is in a synergistically optimized range in terms of intake valve deposit weight, combustion chamber deposit weight, increase in research octane number requirement, increase in heating viscosity, and copper strip corrosion level, demonstrating the ability to simultaneously control low-temperature valve back cleaning and high-temperature combustion chamber deposition suppression. This result indicates that the formulation system is complementary in three aspects: interfacial adsorption, thermal oxidation inhibition, and high-temperature dispersion. On the one hand, the polyetheramine with aromatic side chains has a higher affinity and solubility for polycyclic aromatic hydrocarbon precursors at high temperatures, which helps to maintain the generated fine carbon nuclei in a dispersed state and carry them away from the combustion zone with the airflow. On the other hand, a small amount of grafted structures containing ortho-bisphenol groups may promote the stripping and resuspension of deposits through coordination adsorption with metal / oxide surfaces, and reduce the tendency for oxidative polymerization by free radical capture. Simultaneously, the narrow-distribution polyether skeleton prepared by bimetallic cyanide catalysis exhibits more controllable molecular kinematics and film-forming behavior during combustion and volatilization, reducing the generation of secondary deposition precursors.

[0047] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, the former showed significantly lower deposits in both the intake valve and combustion chamber, and the octane number demand increase and heating viscosity increase were also smaller. The overall trend suggests that the introduction of a small amount of catechol group-grafted components has a positive effect on the entire deposition generation-stripping-resuspension chain. The possible mechanism is that the catechol groups easily form multi-point coordination adsorption on the metal and oxide surfaces, improving instantaneous coverage and wetting, weakening the adhesion strength of the coke precursor, and facilitating its removal by the airflow and fresh fuel film. Its intrinsic antioxidant properties can also intercept free radicals, inhibiting peroxidation and cross-linking under fuel thermal stress. Therefore, the viscosity increase after heating at 180°C is controlled, indirectly reducing high-temperature adhesive deposition. At the same time, the surface conditioning effect improves the film formation / breaking rhythm of the valve back and nozzle, keeping the trace deposits in an easily strippable state, and effectively suppressing the increase in octane number demand after long-term operation.

[0048] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, Example 2 is significantly superior in terms of both types of deposition, octane number increase, and thermal viscosity increase, and also exhibits better corrosion rating. This reflects the enhanced dispersion and resuspension capabilities of high-temperature deposits after the introduction of aromatic side chains. The possible mechanism is that the aromatic side chains improve the compatibility and solubility parameter matching of polycyclic aromatic hydrocarbon precursors and high-carbon-number oxides, forming a more stable dissolution-embedding-migration process and avoiding agglomeration and coking in the high-temperature residence zone of the combustion chamber. Simultaneously, the aromatic structure enhances the adsorption and retention of molecules at the high-temperature interface, weakening the adhesion work between the deposit and the substrate, thereby reducing the measured deposition mass. The decreasing trend in thermal stability data indicates that the oxidative crosslinking pathway is suppressed, reducing adhesive sludge and thus limiting the increase in octane number demand. The better copper strip corrosion rating also suggests that this structure and compatibility system have an inhibitory effect on the formation of acidic intermediates and water-sensitive phase separation.

[0049] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, after adopting the A / B structural gradient compound of Example 2, the deposits in the intake valve and combustion chamber decreased simultaneously, and the increase in octane number demand and the increase in hot viscosity further converged, demonstrating the advantages of structural specialization and proportional synergy. The possible mechanism is that polyetheramines without aromatic side chains are better at rapid swelling and cleaning early deposits on the valve back at lower temperatures, while polyetheramines with aromatic side chains maintain a higher affinity and dispersion stability for hydrophobic carbon nuclei at high temperatures; the A / B compound achieves continuous coverage of low-temperature valve cleaning and high-temperature sedimentation control in the thermal field and polarity gradient, reducing re-adsorption and secondary coking during cross-temperature migration.

[0050] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, excessive enrichment of components containing aromatic side chains leads to increased deposits in the intake valve and combustion chamber, higher octane rating requirements, and increased hot viscosity. The presumed reason is that while aromatic side chains improve high-temperature dispersibility, their high cohesive energy density and interfacial retention tendency, when present in a high proportion, may result in a thicker fuel film forming on the valve back, leading to localized enrichment and dry spot residue, thus increasing the adhesion precursors. Simultaneously, aromatic segments are more prone to condensation in a thermo-oxidative environment, resulting in a larger viscosity increase after heating, promoting deposition adhesion and making peeling difficult. Example 2, by controlling the A / B ratio, achieves a dynamic balance between low-temperature cleaning and high-temperature dispersion, maintaining a thin, easily renewable film while ensuring effective encapsulation and migration of high-temperature precursors, thereby achieving a more balanced technical effect across multiple indicators.

[0051] As can be seen from the data in Example 2 and Comparative Example 5 in Table 1, after changing the chain-growing monomer from ethylene oxide to propylene oxide, the deposition in the intake valve and combustion chamber was significantly reduced, the increase in octane number demand and the increase in hot viscosity converged significantly, and the corrosion level was also improved, showing the comprehensive stability advantage brought about by the introduction of side-chain methyl groups. The possible mechanism is that the polyether segments formed by propylene oxide have more suitable hydrophobic / hydrophilic balance and glass transition characteristics, weakening the tendency for water adsorption and phase separation, and reducing the risk of corrosion on the metal surface under humid and hot conditions; its combustion and volatilization behavior is more controllable, reducing coking in the low-temperature oxygen-rich zone and crosslinking in the high-temperature zone, thereby reducing the two types of deposition and the viscosity increase after heating to 180°C; in terms of combustion phase, less adhesive residue suppresses the abnormal demand under the temperature-pressure coupling at the end of compression, and the increase in octane number demand remains at a low level.

[0052] from Figure 1 As can be seen, compared with terminal amino polyether B, catechol-grafted polyetheramine exhibits significant π–π* characteristic absorption peaks in the 270–290 nm range and a strong absorption band at 200–230 nm, while terminal amino polyether B has weak absorption in this region. This indicates that a chromophore with an ortho-diol aromatic structure was introduced into the sample, which corroborates the successful grafting of catechol groups onto the polyetheramine backbone.

[0053] from Figure 2 As can be seen from the data, the main peak of the gel permeation chromatography of terminal amino polyether B shifts towards a shorter retention time compared to terminal amino polyether A, and the peak shape is narrower and more symmetrical, indicating that the molecular weight is significantly increased after chain growth / secondary amination, while the molecular weight distribution remains relatively narrow.

[0054] from Figure 3 As can be seen from the data, the two samples are at 1110 and 1070 cm⁻¹. -1 Strong C–O–C stretching absorption was observed at all locations, with peak values ​​at 2964, 2933, and 2871 cm⁻¹. -1It exhibits C–H stretching characteristics of –CH3 / –CH2 at 3300–3500 cm⁻¹ -1 The broad peak of the terminal amino group is visible, at approximately 1645 cm⁻¹. -1 The presence of –NH2 shear bending absorption at 30-30 cm⁻¹ indicates that both are terminal amino polyether structures. Compared to terminal amino polyether A, terminal amino polyether B exhibits stronger absorption at 30-30 cm⁻¹. -1 Aromatic C–H stretching occurs at 1600, 1585, and 1495 cm⁻¹. -1 A characteristic C=C stretching peak of the aromatic ring appears at 750 and 700 cm⁻¹. -1 The presence of aromatic C–H out-of-plane bending absorption at this point clearly demonstrates the introduction of a phenyl side chain into the terminal amino polyether B. Neither spectrum showed an absorption at approximately 910 cm⁻¹. -1 The characteristic peaks of the epoxy indicate that the residual epoxy end has been basically opened. In summary, the terminal amino polyether B successfully introduced a benzene ring structure while retaining the polyether skeleton.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A fuel system detergent, characterized in that, It is prepared from the following raw materials in parts by weight: 100-150 parts of terminal amino polyether A, 150-200 parts of terminal amino polyether B, 2-5 parts of catechol-grafted polyether amine, 440-460 parts of toluene, 190-210 parts of heavy aromatic oil, 12-18 parts of 2,6-di-tert-butyl-4-methylphenol, 7-9 parts of N,N'-disalicylic acid-1,2-propanediamine, and 20-30 parts of isopropanol; The terminal amino polyether A is obtained by ring-opening polymerization of propylene oxide with methanol as an initiator in the presence of a bimetallic cyanide catalyst to obtain terminal hydroxyl polypropylene glycol, and then amination of the terminal hydroxyl polypropylene glycol with hydrogen and anhydrous ammonia in the presence of Raney nickel. The terminal amino polyether B is obtained by: taking terminal amino polyether A and styrene carbonate to introduce phenyl side chains through amino ring opening to form terminal hydroxy carbamate, and then continuing to ring open chain growth with propylene oxide in the presence of a bimetallic cyanide catalyst to obtain a chain extension product. The chain extension product is then subjected to secondary amination with hydrogen and anhydrous ammonia in the presence of Raney nickel to obtain terminal amino polyether B. The catechol-grafted polyetheramine is a grafted product obtained by reacting terminal amino polyether B with dopamine glycidyl ether in dimethylformamide in the presence of triethylamine, followed by solvent removal, precipitation washing, and drying.

2. The fuel system detergent according to claim 1, characterized in that, The raw materials for preparing the terminal hydroxyl polypropylene glycol are, by weight, 20 parts methanol, 4 parts bimetallic cyanide catalyst, and 200-280 parts propylene oxide.

3. The fuel system detergent according to claim 1, characterized in that, The raw materials for preparing the terminal amino polyether A are, by weight, 300 parts of terminal hydroxyl polypropylene glycol and 14-18 parts of Raney nickel.

4. The fuel system detergent according to claim 1, characterized in that, The hydrogen partial pressure during the preparation of terminal amino polyether A is 2.8-3.2 MPa, and the total pressure is 5.8-6.5 MPa; the hydrogen partial pressure during the preparation of terminal amino polyether B is 2.8-3.2 MPa, and the total pressure is 5.8-6.5 MPa.

5. The fuel system detergent according to claim 1, characterized in that, The raw materials for preparing the chain extension product are, by weight, 180 parts of terminal amino polyether A, 50-80 parts of styrene carbonate, 1.5-2.5 parts of bimetallic cyanide catalyst, and 40-80 parts of propylene oxide.

6. The fuel system detergent according to claim 1, characterized in that, The raw materials for preparing the terminal amino polyether B are, by weight, 200-240 parts of chain extension product and 10-14 parts of Raney nickel.

7. The fuel system detergent according to claim 1, characterized in that, The hydrogen partial pressure during the preparation of the terminal amino polyether B is 2.8-3.2 MPa, and the total pressure is 5.8-6.5 MPa.

8. The fuel system detergent according to claim 1, characterized in that, The raw materials for preparing the catechol-grafted polyetheramine are, by weight, 20 parts of terminal amino polyether B, 2-5 parts of dopamine glycidyl ether, 120 parts of dimethylformamide, and 1.5-2.5 parts of triethylamine.

9. A method for preparing a fuel system detergent according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Preparation of bimetallic cyanide catalyst: Zinc chloride was dissolved in deionized water, and potassium hexacyanocobaltate was dissolved in deionized water and then slowly added to the above solution. Tert-butanol and polyethylene glycol 400 were added and stirred for 100-140 min. The mixture was then allowed to stand for aging, filtered and washed alternately with deionized water and tert-butanol, and dried under reduced pressure to obtain the bimetallic cyanide catalyst. (2) Preparation of terminal hydroxyl polypropylene glycol: Methanol is added as an initiator and a bimetallic cyanide catalyst in a pressure-resistant reactor, propylene oxide is introduced, and the reaction is carried out under heating and stirring conditions. The reaction temperature is 85-95℃ and the time is 150-210min. Unreacted methanol and trace monomers are removed under reduced pressure, and the catalyst is removed by filtration to obtain terminal hydroxyl polypropylene glycol. (3) Preparation of terminal amino polyether A: Terminal hydroxyl polypropylene glycol and Raney nickel are loaded into a pressure-resistant reactor, hydrogen and anhydrous ammonia are introduced to pressurize the reactor, and the reaction is carried out under heating and stirring conditions. The reaction temperature is 125-135℃ and the time is 210-270min. The reactor is cooled, vented and filtered, and residual ammonia and water are removed under reduced pressure to obtain terminal amino polyether A. (4) Introducing phenyl side chain and chain growth: Add styrene carbonate to the terminal amino polyether A, stir and react at 75-85℃ for 150-210 min to generate terminal hydroxyl carbamate with phenyl side chain from the terminal amino ring-opening cyclic carbonate. Then add bimetallic cyanide catalyst and propylene oxide and chain grow at 85-95℃ for 150-210 min to obtain chain-extended product; (5) Preparation of terminal amino polyether B: The chain extension product and Raney nickel are loaded into a pressure-resistant reactor, hydrogen and anhydrous ammonia are introduced to pressurize the reactor, and the reaction is carried out at 125-135℃ for 210-270 min to complete the amination. The reactor is cooled, filtered and the residual ammonia is removed under reduced pressure to obtain terminal amino polyether B. (6) Preparation of dopamine glycidyl ether: Dopamine hydrochloride and sodium hydroxide were dissolved in deionized water, and epichlorohydrin was added dropwise after cooling. The mixture was stirred at 30°C for 360 min, extracted with ethyl acetate, washed with water, and the solvent was removed by vacuum evaporation to obtain dopamine glycidyl ether. (7) Preparation of catechol-grafted polyetheramine: terminal amino polyether B and dopamine glycidyl ether are dissolved in dimethylformamide, triethylamine is added, and the reaction is stirred at 45-55℃ for 210-270 min to complete the grafting. After removing the solvent under reduced pressure, the product is precipitated with anhydrous diethyl ether, washed and dried to obtain catechol-grafted polyetheramine. (8) Preparation of detergent: Terminal amino polyether A, terminal amino polyether B and catechol-grafted polyether amine are stirred evenly at 40°C to obtain a mother liquor. Toluene, heavy aromatic oil, 2,6-di-tert-butyl-4-methylphenol, N,N'-disalicylic acid-1,2-propanediamine and isopropanol are added and stirred at room temperature. The mixture is allowed to stand to degas and then filtered to obtain a fuel system detergent.

10. The method for preparing the fuel system detergent according to claim 9, characterized in that, In step (6), by weight, there are 15 parts of dopamine hydrochloride, 6 parts of sodium hydroxide, 80 parts of deionized water and 25 parts of epichlorohydrin.

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